This invention relates generally to automotive trim parts and, more particularly, to a sound deadening method for reducing noises such as buzzes, squeaks and rattles that are generated by adjacent trim parts rubbing together.
Motor vehicles commonly include interior trim components such as switch plate bezels, demisters, light housings, speaker covers, decorative appliques, storage compartments and the like that are attached within portions of interior trim panel surfaces of such vehicles. Examples of trim panels that such components are commonly installed in include instrument panels, door panels, headliners, package trays, seats and center consoles. The trim panels are often made of laminated material and include an outer layer that displays a decorative appearance. Adjacent trim panels are usually designed to fit together closely or to partially overlap with only a narrow seam separating them.
This close fit between trim panels and components mounted in the panels or between adjacent trim panels often results in noises, such as buzzes, squeaks and rattles, that result from contact and relative motion between surfaces of edges of adjacent trim parts. This noise is sometimes referred to as BSR (buzz, squeak, rattle) or NVH (noise, vibration, harshness). To mitigate the BSR/NVH problem, some production automobile assemblies apply a buffer material in the form of flat adhesive-backed tape (BSR tape) to one or both mating surfaces (typically panel edges) between adjacent trim parts. However, the tape application process is labor-intensive and can result in exposed tape that vehicle occupants can see, thus detracting from the finished appearance of a vehicle interior.
To reduce labor requirements and improve quality, some systems apply buffer material in the form of extruded elastomers rather than tape. The buffer material is extruded onto the mating surface and/or surfaces by an applicator in the form of an extruder head and allowed to cure before assembly. In some such systems extruder head movement is robotically controlled. One problem with adapting these systems to use in applying buffer material to automotive trim is that it is difficult to adhere elastomers to all the materials used to form automotive trim components and panels. Trim assemblies sometimes include mating trim parts that are made of several different materials, e.g., PVC, PP, PC/ABS, ABS, paint, wood, textiles, etc. It would be difficult to provide a robotic applicator system that could cost-effectively apply different buffer materials to all these different trim materials. To do so would likely require either multiple robotic applicators, each applying a different buffer material, or a single applicator capable of rapidly and repeatedly changing the type of buffer material it applies.
It is known to augment the holding power of hot melt adhesives by applying such adhesives to a groove in such a way as to form a mechanical as well as an adhesive bond between adjacent parts. For example, U.S. Pat. No. 3,635,117 issued to Nagao on Jan. 18, 1972 discloses a method for fixing a woodwind instrument. The method includes the step of forming a groove in an outer surface of the instrument and a corresponding groove in an inner surface of a repair ring shaped to fit around the instrument. Hot melt adhesive is then introduced into the groove in the instrument and onto adjacent surfaces of the instrument. The ring is then joined to the instrument such that the grooves are facing one another. The adhesive is then heated into a melted state. When the adhesive cools and cures it provides both an adhesive bond between the parts and a mechanical lock against shear forces where it has dried within the facing grooves. The Nagao patent does not disclose how the instrument is grooved or how the adhesive is applied.
What is needed is a sound deadening method for interior vehicle trim parts that can provide a bead of a single buffer material between adjacent parts by applying the bead to one or both vehicle interior trim parts even where the parts have differing material compositions. What is also needed is apparatus configured apply the buffer material.
A method is provided for mounting interior vehicle trim parts in which a first trim part is supported adjacent a second trim part and in which a bead of buffer material is mechanically locked into a recess in one of the first and second trim parts. The bead is included to reduce noises such as buzzes, squeaks and rattles that might otherwise be produced by contact and relative motion between the first and second trim parts. According to the method, the first trim part is provided having a mating surface configured to lie alongside a mating surface of the second trim part when the first and second trim parts are supported adjacent one another in a vehicle. The recess is then formed in the mating surface of the first trim part and the buffer material is provided in the recess. The buffer material is provided in such a way as to provide a bead of buffer material on the mating surface of the first trim part. The bead is allowed to mechanically connect to the first trim part because of the hardening of the buffer material within the recess.
The first and second trim parts are then supported adjacent one another with the second trim part contacting the bead of buffer material.
According to another aspect of the inventive method, the recess is formed to include an undercut to more positively lock the hardened buffer material onto the mating surface of the first trim part.
According to another aspect of the inventive method, the buffer material preferably comprises an elastomeric material. A suitable elastomeric buffer material is preferably selected from a group consisting of thermoplastic elastomers (TPEs) and thermosetting elastomers. Thermoplastic urethane (TPU) is a preferred form of TPE to be used as the buffer material.
According to another aspect of the inventive method, buffer material is provided in the recess by providing an applicator comprising an extrusion head and extruding buffer material through the extrusion head and into the recess.
According to another aspect of the inventive method, in forming the recess a robot is operatively connected to a recess-forming tool and the robot is operated in such a way as to move the forming tool into and along the mating surface of the first trim part.
According to another aspect of the inventive method, in providing buffer material a robot is provided that is operatively connected to an applicator. A source of buffer material is connected to the applicator such that the buffer material is in fluid communication with the applicator. The robot is then operated in such a way as to move the applicator in spaced generally parallel relationship with the mating surface of the first trim part while projecting buffer material into the recess and onto the mating surface.
According to another aspect of the inventive method, in providing the buffer material an applicator is operatively connected to the robot adjacent the recess-forming tool. A source of buffer material is then connected to the applicator in such a way as to be in fluid communication with the applicator. The robot is then operated in such a way as to simultaneously move the forming tool into and along the mating surface of the first trim part while moving the applicator in spaced generally parallel relationship with the mating surface and in trailing relationship to the recess-forming tool. The trailing applicator provides buffer material in the recess formed by the preceding forming tool, overfilling the recess and providing a bead of buffer material on the mating surface of the first trim part.
According to another aspect of the inventive method, the forming tool provided includes a router having a router bit configured to form a recess of desired cross sectional shape.
According to another aspect of the inventive method, the second trim part is configured to be mounted in an opening in the first trim part, the mating surface of the second trim part being an outer peripheral edge of the second trim part. Likewise, the mating surface of the first trim part is an inner edge of the first trim part that surrounds and defines the opening in the first trim part.
Also according to the invention, a bead forming apparatus is provided for forming a bead of buffer material on a mating surface of an automotive trim part according to the above method. The bead forming apparatus comprises a recess-forming tool and an applicator on a common mount. The recess-forming tool is configured to form a recess in the mating surface. The applicator is configured to provide buffer material in the recess and to form a bead on the mating surface by overfilling the recess. A drive is operatively connected to the common mount and is configured to move the recess-forming tool and the applicator simultaneously with respect to the mating surface with the applicator trailing the recess-forming tool. A source of buffer material is in fluid communication with the applicator and is configured to supply the buffer material to the applicator. By mounting both the recess-forming tool and the applicator on the same mount and driving them together, the recess may be formed and the buffer material applied in the same manufacturing step.
According to another aspect of the invention, the recess-forming tool is configured to form a recess that includes an undercut. The undercut provides a secure mechanical lock between the bead and the mating surface.
According to another aspect of the invention, the forming tool comprises a router. The router efficiently forms the recess and the undercut in one operation.
According to another aspect of the invention, the applicator comprises an extruder head configured to extrude buffer material into the recess and onto the mating surface.
According to another aspect of the invention, the drive includes a robot having a multi-axis drive system. The robot and drive system provide accurate, consistent application resulting in the formation of a uniform bead.
According to another aspect of the invention, the recess-forming tool and applicator are mounted on an arm of the robot. The arm allows the robot to move the recess-forming tool and applicator along mating surfaces of a variety of shapes and sizes.
According to another aspect of the invention, the applicator is movably mounted relative to the recess-forming tool. In addition, the robot multi-axis drive system is configured move the applicator independent of the recess-forming tool while simultaneously moving the recess-forming tool and the applicator along the mating surface. This allows the applicator to be positioned, to a certain extent, independently from the recess-forming tool. This results in greater control over bead size and placement.